We study core-dominance parameter R and polarization for blazars detected by Fermi LAT. Our results are as follows. (i) The blazars detected by Fermi LAT have higher average R and polarizations than those not detected by Fermi LAT. (ii) Compared with BL Lacs, flat-spectrum radio quasars (FSRQs) have lower average R and the ratio of beamed luminosity to the unbeamed luminosity f. (iii) In the diagram of polarization-Doppler factor relations, FSRQs may have p=α+3 and BL Lacs for p=α+2. These results suggest that the high optical polarization is correlated to the beaming effect. High polarization and core-dominance parameters are significantly more common among the LAT sources. The difference in polarization and core-dominance parameters between FSRQs and BL Lacs are due to the difference in their beaming effects and jet model. 相似文献
Slopes in geotechnical and mining engineering are the most crucial geo-structure. Predicting or forecasting the stability or instability of the slope and then classifying the slope accordingly helps in mitigating the risks and enhancing the design by maximizing the safety. Computing techniques have overpowered the analytical and statistical models used for predicting the stability of the slopes. To reduce the uncertainties and ambiguity of the previously used models, lately, researchers have come up with the novel techniques for Slope Stability Classification (SSC) which are Random Forest, Gradient Boosting Machine, Extreme Gradient Boosting, Boosted Trees and Classification and Regression Trees. These computational algorithms are employed in this research paper and the slope details are taken from a literature i.e. 221 input datasets are used and slopes are classified accordingly using the mentioned models. The relation between the inputs such as height (H), slope angle (β), cohesion (c), pore water pressure ratio (ru), unit weight (γ), angle of internal friction (φ) and slope stability (output) is established and slopes are categorized according to their failure and stability. Performance analysis is done thereafter to analyses and compare different models and let the readers and researchers know that which model sufficed and fitted best to the study.
How the Hadley circulation changes in response to global climate change and how its change impacts upon regional and global climates has generated a lot of interest in the literature in the past few years. In this paper, consistent and statistically significant poleward expansion of the Hadley circulation in the past few decades is demonstrated, using independent observational datasets as proxy measures of the Hadley circulation. Both observational outgoing longwave radiation and precipitation datasets show an annual average total poleward expansion of the Hadley cells of about 3.6° latitude. Sea level pressure from observational and reanalysis datasets show smaller magnitudes of poleward expansion, of about 1.2° latitude. Ensemble general circulation model simulations forced by observed time-varying sea surface temperatures were found to generate a total poleward expansion of about 1.23°latitude. Possible mechanisms behind the changes in the horizontal extent of the Hadley circulation are discussed. 相似文献